my att 9700 came with os 205 on it i have upgraded 4 times now no problem .i have not used a single att os to upgrade. all my upgrades were done with non att os.but i used different programs to upgrade the os.i never use desktop manager .i have used loader.exe ,bb sak ,and shrink an os .i liked bbsak because i can backup my 3rd party apps.i do the upgrade and the the 3rd party apps.